Apple has another winner with Mac OS X 10.6, also known as Snow Leopard. This version of the Macintosh operating system, which goes on sale Friday, August 28, is the brainiest, brawniest, and most beautiful consumer-oriented OS available anywhere—and it ships with the best built-in applications and utilities you can find. As its name suggests, this latest version builds on the strong foundation of its predecessor, OS X 10.5 (Leopard), and offers a smooth upgrade path for existing users—any Intel-based Mac will run it. You’re out of luck if you still have a PowerPC-based Mac—Snow Leopard installs on Intel-based Macs only. (A note about pricing: Apple’s official line is that an update from Leopard costs $29, or $49 for a five-license family pack but that OS X 10.4 —aka Tiger— users will need to buy a $169 package called the Mac Box Set containing Snow Leopard, iLife ‘09, and iWork ‘09. In fact, the Snow Leopard DVD will upgrade Intel-based Tiger machines as well as Leopard machines. With either the single Snow Leopard disc or the Mac Box Set, Tiger users should be careful to update their applications before upgrading, because Tiger-era applications are far more likely to need updating to be fully compatible with Snow Leopard.)